A conventional cartridge casing 10 is shown in FIG. 1. The cartridge assembly 10 comprises a casing 12 and a projectile 14. The casing 12 has a hollow section 16 which will contain propellant (or “charge”) for displacement of the projectile 14. The casing 12 further comprises an integral head 18 at the end opposite to the projectile 14 which comprises a chamber 20 for a percussion cap, and a flash tube 22 for communication of an ignition charge from the percussion cap to the inside of the casing 12 and thus the propellant. The walls of the chamber 16 are formed integrally with the head 18. Such a cartridge casing may typically be formed of brass. This material choice has many advantages, for example, it is relatively easy to form into the desired shape. However, brass has demerit in that it is also relatively dense, and hence the casing 12 forms a relatively large percentage of the mass of the whole cartridge.
Side and end views of a conventional blank ammunition round (i.e. without projectiles, for training purposes) is shown in FIG. 2. These may be manufactured using the same basic processes as used for conventional cartridge cases. They comprise an extended cartridge casing 12′ such that an open end 30 of the casing wall is extended to take up the space normally occupied by the bullet 14 in a live round. The open end 30 is closed by way of a “petalled” crimp 38 which is sealed using a liquid varnish/adhesive like sealant. The blank round is closed at its other end by an integral head cap 18′ formed as one piece with the walls of the casing 12′. This configuration defines a chamber 20′ for a percussion cap 32, and a flash tube 22′ for communication of an ignition charge from the percussion cap 32 to the hollow interior 16 inside the casing 12 to thus ignite a propellant (or “charge”) 36 provided therein. On firing the pressure in the casing 12′ builds up, and then opens up the front closure, the resultant energy delivered being used to operate the weapon system. This design tends to suffer from sealing problems around the crimp, leading to misfire and jamming of the weapon system.
Thus a cartridge casing for a blank ammunition round which is more reliably sealed, thus resulting in more reliable operation, is highly desirable.